The Response: Status Line, Headers, Body

The answer comes back wearing the same suit. A response — what the server sends in reply — has the same three-part anatomy as the request: a leading line, then headers, then a body. It is the mirror image of what you sent, and having learned one side, you already mostly know the other.

Here is what comes back when the app asks about Old Market — the actual reply to the last page's request:

HTTP/1.1 200 OK
Content-Type: application/json
Date: Thu, 20 Aug 2026 09:14:07 GMT

{"id": "st_014", "name": "Old Market", "capacity": 24,
 "free_bikes": 9, "status": "active",
 "location": {"lat": 47.21, "lon": 8.55}}

The Status Line: the Verdict

The response leads with HTTP/1.1 200 OK — dialect, number, phrase. The number is a status code: the server's one-glance verdict on your request. 200 means it worked. The phrase after it is just the number in words. Two pages from now you will learn to read the whole family of these numbers at a glance; for now, know where the verdict sits — first line, always.

Response Headers: the Server's Envelope Notes

Then headers, same format as yours: Name: value, one per line, now written by the server. The one to meet today is Content-Type: application/json — the label announcing what kind of thing the body is. Here it says JSON, the data format Chapter 4 teaches you to read. Other notes will matter later: counters that track your request allowance (Chapter 8), identifiers that help support find your request in their logs (Chapter 7). The habit is the same as the last page: the envelope notes are short, and they are worth a glance.

The Body: the Actual Answer

After a blank line comes the body — the thing you asked for. Old Market, station st_014, capacity 24, nine bikes free right now, active, and its coordinates. You can already read most of it cold, which is the point of showing it before JSON gets its formal introduction. The braces and brackets have exact rules, and Chapter 4 makes you fluent in them; but notice that even now, nothing in this answer is intimidating. It is a luggage tag's worth of facts about one bike station.

One Conversation, Both Halves

Put the two pages together and you have the complete atom of this book. A handful of lines out; a verdict, a few notes, and an answer back. Every page ahead — keys, errors, pagination, webhooks — is this same exchange with one detail turned up. When Vera watches her first live conversation in the next chapter, she will recognize both halves on sight. So will you.